1.6.0 - 2023-06-28

What's new:

• Merge 1.5.0 - 1.5.3, in brief:
  • Add BDevices::Keys constructor by key code
  • Fix BDevices::Keys::KeyType based on uint32_t
  • Add static converters for BDevices::Keys::KeyType and key code
    (uint32_t)
  • Implement emit key events to widgets which grabbed selected keys
  • Add the flag entered_ to mark entered widgets
  • Add substeps to BWidgets::ValidatableRange
  • Implement substep scrolling and dragging if shift key pressed in (image-)
    dial, scale, scrollbar widgets, and pads
  • Add keyboard control (cursor keys, +/-) to dials, sliders, scrollbars, pad,
    and pattern
  • Update documentation